VANCOUVER, July 6 (Reuters) - Air Canada ACa.TO ACb.TO and WestJet Airlines (WJA.TO), Canada’s two biggest carriers, flew emptier planes in June but both were optimistic about a pickup during the busy travel months in the summer.

Air Canada, the country’s biggest carrier, said on Wednesday its system-wide load factor, which includes regional airlines from which it purchases capacity, dipped to 84.2 percent in June from 84.7 percent in the same month a year earlier.

That was because the capacity across its fleet rose 3 percent last month, while traffic rose just 2.5 percent, it said.

The airline flew 122,000 passengers on the last day of June 2011, “a record for a single day as we head into the peak summer travel season”, Air Canada Chief Executive Calin Rovinescu said in a statement.

July and August are traditionally the two busiest months of the year for Canadian airlines .

Air Canada’s biggest domestic competitor, WestJet, said its planes were also emptier in June, resulting in its load factor dropping to 75.7 percent from 78.2 percent in June 2010, a weaker result than analysts had expected.

“Although loads were slightly down for June, ... We are pleased with the advanced bookings for July and August, and the pricing environment continues to be strong,” said Gregg Saretsky, WestJet’s chief executive.

Analysts stayed optimistic about WestJet’s longer-term prospects.

“With forward bookings strong and the pricing environment still favorable, we expect solid year-over-year unit revenue improvements to continue into the third quarter,” National Bank Financial analyst Cameron Doerksen said in a note to clients.